Ultra-Endurance Medicine


November 4th 2020

5:00PM - 6:00PM EST

Ultra-Endurance Medicine: Drowning from Hydration Advice: Tales of Exercise-Associated Hyponatremia in Endurance Competitions and the Wilderness

Dr. Marty Hoffman

Ultra-Endurance Medicine: Drowning from Hydration Advice: Tales of Exercise-Associated Hyponatremia in Endurance Competitions and the Wilderness



Do you alter your fluid and electrolyte intake a few days before a race? If so, what is your routine? I recommend just assuring you are properly hydrated.

No need to super hydrate and be up repeatedly during the night before the race to urinate or stop early in the race to urinate.

Most ultramarathons I’ve seen did weight measurements at their clinical checkpoints… do you recommend other screenings for hyponatremia?

This was a carry over from the medical checks of horses when humans started doing the Tevis Cup horse race before the human race (Western States 100 mile Endurance Run) was established. Our work showed that the concern over weigh-in was promoting overhydration at this event, so we eventually removed the weighing. In situations where the mentality may be a little different, then weight checks, largely looking for inadequate weight loss or weight gain, can be useful to identify who might be overhydrating. It’s important that the scales are accurate, on hard level surfaces, and that the weight measurements are made without extra clothing, pack, etc. on the body. When this cannot be achieved, then I would recommend avoiding weight checks since the data cannot be trusted.

How do you best distinguish between hyper vs. hyponatremia - are there symptoms that signify one over the other? i.e. Nausea → hypo?

It’s not really possible to distinguish with symptoms, or even with physical findings. Getting a history about fluid intake is the best way in the field, unless you can get a point-of-care sodium analysis.

Do NSAID’s influence inappropriate AVP secretion? I.e. is it safe to take NSAIDs during prolonged endurance events?

Theoretically, they may, but in practicality they probably have little, if any, effect. On the other hand, there is little evidence that the help in terms of pain. I think acetaminophen is a better option if one needs a pill for pain relief during these events.

Can you speak to hypo/hyperkalemia on the trail? On a recent R3 attempt at the Grand Canyon, I had 3000 mg of sodium that I thought would get me through the round trip. but I ran out when I hit the North Rim and had a lot of muscle cramping. I realized my supplement didn't have any potassium. I'm not sure if this is reason or if my nutrition in general was off.

The current thought is that muscle cramping in this situation (endurance exercise) is generally due to muscular fatigue rather than a fluid or electrolyte imbalance.

How do you get involved as a med-student/physician in ultra-endurance medicine? What role do you play at races? Is this something we can help with as medical students?

Run an ultramarathon and get to know the folks involved, and ask to volunteer. Otherwise, find out when there is a local race or try to contact the race or medical director in advance and ask to help. Big races often have various volunteer opportunities. You might largely be asked to serve as a general volunteer (hand out food and fluids), but if you are placed at a station with medical, then you can indicate your interest. You might be taught blister management, and do some of that.

I’ve heard that you can’t overcorrect hyponatremia if it’s only been a few hours… is this true from your experience?

Probably not true. But, if you treat within the guidelines I noted, the overcorrection will be minimal and not cause harm. Perhaps you are getting confused with the issue of central pontine myelinolysis, which is not felt to be a concern with rapid treatment of hyponatremia.

Do you keep 3% NS at ultra-events?

It depends on the event. Large events should have IV hypertonic saline. Smaller events will generally not, and may not even have on-site physicians.

I noticed your statistic that 51% of people completing 100-mile endurance runs have EAH? Is this still true with updated guidelines?

That was what we found in our initial study in 2008, and the same percentage was found in anther study a few years earlier. The incidence has gone way down in the events where we’ve done our studies to around 6% at the most recent studies.